Propeller



April 1, 1941. I

J. M. MILLS PROPELLJER Filed May 19, 1931 Patented Apr. 1, 1941PROPELLER James M. Mills, Helena, Mont., assignor, by mesne assignments,South Bend,

to Bendix Aviation Corporation, Ind., a corporation of DelawareApplication May 19, 1931, Serial No. 538,553 12 Claims. (Cl. 170-163)This invention relates to propellers and more particularly to variablepitch propellers which may be particularly adaptable for use onaircraft.

One of the objects of the present invention is to provide novel meansand mechanism for varying the pitch or angularity of the blades of apropeller while the latter is in operation, whereby the propeller may beoperated at maximum emciency under varying conditions.

Another object of the invention is to provide in a variable pitchpropeller, novel means responsive to fluid pressure for varying thepitch of the blades.

Another object is to provide in a variable pitch propeller, novel meansresponsive to centrifugal .force for varying the pitch of the bladestogether with a selectively operable mechanism for. determining theextent of operation of the pitch varying means whereby the pitch of theblades may be easily and quickly changed to the desired value.

Still another object is to provide in a propeller of the above characterwherein centrifugallyresponsive means are employed for securing anincreased pitch of the blades, novel means for reducing or reversing thepitch.

A further object is of the above type. thermal-responsive means forvarying the pitch of the blades together with mechanism whereby thesupply of energy thereto may be readily regulated.

A still further object is to provide in a variable pitch propellerembodying centrifugally-respon sive members for increasing the pitch ofthe blades, mechanism actuated by the expansion of a fluid in responseto heat supplied thereto, for controlling the operation of the memberstogether with a novel arrangement for controlling the amount of heatsupplied the fluid, thereby permitting the blades to be moved to assumevarious pitch angles.

The above and other objects of the invention will appear more fullyhereinafter from the following detailed description when taken inconnection with the accompanying drawing wherein there is illustratedone embodiment of the invention. It is to be expressly understood,however, that the drawing is for the purpose of illustration only and isnot designed as a definition of the limits of the invention, referencebein had for this purpose to the appended claims.

In the drawing, wherein similar reference numerals refer to similarparts throughout the several views:

to provide in a propeller I Fig. 1 is an axial section of a propellerconstructed in accordance with the present invention; and

Fig. 2 is a fragmentary view in section of certain of the partsillustrated in Fig. 1.

Referring more particularly to Fig. 1, a variable pitch propellerembodying the principles of the present invention is illustrated thereinas embodying a hub 3 adapted to be driven by a rotatable shaft 4, whichmay be the crankshaft or an extension thereof of an internal combustionengine, the said hub being provided with a plurality of radiallyextending sockets 5 within each of which the root end 6 of a blade 1 isrotatably mounted. Only a portion of the blades 1 is illustrated inorder that a large scale drawing may be employed.

In order to drivably connect the hub 3 to the shaft 4, the latter isprovided with a plurality of keys or splines 8 which are adapted tocooperate with similar splines formed on the hub. Preferably, the hubcooperates with split front and rear cones 9 and I0 respectively,interposed between the drive shaft and hub for properly positioning thelatter. As illustrated, the cone 9 may be threaded upon the outer end ofthe shaft and suitably locked thereon as by means of a threaded ring ll.As heretofore stated, the roots 6 of the blades are rotatably mounted inthe hub sockets, and as shown, such mounting may be efl'ected bybearings l2 and I3, the latter serving also as a thrust bearing.

.Means are provided for varying the pitch of the blades, and preferablysuch means include members responsive to the centrifugal force developedtherein during operation of the propeller. As shown, such means isconstituted by a member it which maybe a weighted ring or collarsurrounding the socket 5. For the purpose of operatively associating themember It with the propeller blades in order that longitudinal movementof the former may produce rotation of the latter about theirlongitudinal axes, a shaft l5 connected to diametrically opposedportions of the ring I extends through the socket 5 and through theblade root 6 by reason of the provision of diagonally extending slots l6and I1 disposed on pposite sides 'of the blade root. The shaft l5 alsoextends through slots l8 and i9 provided in either side of the hubsocket, and these slots preferably extend longitudinally of the axis ofthe blades. From the above it will readily be apparent that duringlongitudinal movement of the members H, the shafts l5 will cooperatewith the diagonally extending slots ll and I! to rotate the blades abouttheir axes and thus vary the pitch thereof, it being borne in mind thatthe members |4 are prevented from rotating by reason of the co-operationbetween the shafts |5 and the longitudinally extending slots [6 and |9.

Outward movement of members i4 causes the shafts I5 and grooves I6, I?and I9 to effect an increase in the pitch of the blades.

In order to secure lower pitch settings of the propeller blades, fluidpressure means are provided, which in operation serve to control theefiect of the above described centrifugally-responsive means.Preferably, such fluid pressure means is constituted by a confined bodyof liquid which is thermally-responsive in such a manner that the volumethereof varies in response to heat supplied thereto to cause relativemove-|- ment between the hub and centrifugallyresponsive means. tuted bya fluid operated device having relatively movable cylinder and pistonportions 2| and 22 respectively, the former being guided in its axialmovement by a flange 23 on the hub 3, and preferably having its exteriorcontour so formed as to increase the aerodynamic efliciency thereof. Thecylinder 2| is provided interiorly with a bore 24, supported by adiaphragm 25 which latter, together with the head 26 of the piston 22within the bore and rigidly connected with the drive shaft 4, serve toconfine within the cylinder, a suitable thermal-responsive liquid suchas, for example, mercury. As illustrated, the piston 22 is rigidlyconnected to the drive shaft 4 by means of a nut member 21, there beingprovided a pair of oppositely disposed openings 28 and 29 in said memberfor receiving a pair of axially extending arms 30 and 3| respectively,which may be formed integrally with the cylinder 2|. It will thus beobserved from the above that relative movement between the cylinderportion 2| and the piston portion 22 will eflect axial movement of bothof the arms 30 and 3|.

In order tooperatively connect the arms 30 and 3| with thecentrifugally-responsive members |4 so that longitudinal movement of theformer will efl'ect a control of the position of the latter and hence avariation of the pitch of the blades, the inner portion of each of saidarms is formed with teeth 32 which are adapted to mesh with a pinion 33rotatably mounted in the drive shaft 4, in any suitable manner, as bymeans of a shaft 34 to which the pinion is drivably connected. Drivablysecured to the shaft 34 is a pulley 35 to which one end of a suitablecable or chain 36 is secured, the other end thereof being attached tothe shaft 5. From this construction, it will be apparent that movementof arms 30 and 3| to the right, as viewed in Fig. 1, will permit themembers I4 to be moved outwardly in response to centrifugal force toincrease the pitch of the blades, while movement of the rods to the leftwill move the members |4 inwardly by reason of the cable 36 winding onthe pulley 35, to decrease the pitch of the blades.

Means are provided for supplying heat to the body of fluid confinedwithin the device 26 and for thus controlling the operation of thelatter, and preferably such means is constituted in such a manner as toinclude a plurality of electrical circuits which may be selectivelyactuated to secure various adjustments of the pitch of the blades. Asshown, such means embodies a switch casing 31 preferably formed ofinsulating material suitably secured to the shaft 4 and provided withthree portions 38, 39, and 40 adapted to 75 As shown, such means isconstiform switch housings for relatively movable contacts 4| and 42.The contacts 4| are carried by each of the inner ends of a plurality ofarms 43, secured to the arms 30 and 3| in any suitable manner, while thecontacts 42 are each electrically connected to conductingresilientmembers or springs 44. Each of the latter is connected to a slip ring bymeans of a conductor 46, each of the slip rings being carried by the hub3 and suitably insulated therefrom. It will be observed that each of theswitch housings 33, 39, and 40 is provided internally with a pluralityof stops 41 of variable length which cooperate with contacts 42 carriedby the ends of members 44 to limit expansion of the latter for a purposewhich will appear more fully hereinafter. In order to supply energy toeach of the slip rings 65, the latter are connected through brushes 41and remotely located independently controlled switches 48, 69, and toone terminal of a bat.- tery 5|, the other terminal thereof beingpreferably grounded. Each dLthe contacts 4| may be electricallyconnected with one terminal of a plurality of removably mountedelectrical resistance units 52 by wires 53, 54, and 55, and the otherterminals of said units may be grounded to the cylinder 2 l.

The parts as illustrated in Fig. 1, wherein switch 49 is closed,illustrate a low pitch position of the blades while the propeller is inoperation, With switches 46, 49, and 50 open and the propeller inoperation, the centrifugally-responsive members l4 will move radiallyoutwardly and the shafts I5 carried thereby will cooperate with thediagonally arranged slots l6 and H, as heretofore described to rotatethe blades in their sockets to a position of maximum pitch. It is to beparticularly noted that during this operation, each of the pinions 33will rotate and move the cylinder 2|, arms 30 and 3| and arms 43 towardthe right, as viewed in Fig. 1, whereby all the contacts 4| and 42 willbe brought into onerative engagement and resilient members 44 placedunder compression. If it benow desired to reduce the pitch of thepropeller blades to a low position, switch 49 may be closed to establisha circuit to the heating elements 52 from the battery 5| through switch49 and associated brush 41 slip ring 45, lead 46, the centrally locatedresilient member 44, engaged contacts 42 and 4| and conductors 53, 54,and 55, whereby the fluid within the device 20 will be heated.

Upon the application of heat to the fluid, the latter will expand andeffect relative movement between the cylinder 2| and piston 22 to movethe arms 39 and 3| toward the left, as viewed in Fig. 1, such movementresulting in rotation of the pinions 33, whereby the cable 36 will drawthe centrifugally-responsive members l4 inwardly, and such movement ofthe latter will reduce the pitch of the blades by reason of thecooperation between the shaft l5 and the slots I6 and I1. It will alsobe observed that the arms 43 will also be moved toward the left, thecontacts 4| and 42, however, remaining in operative relation until thelatter reaches the stop 4'|'whe upon further movement thereof to theleft is positively arrested. Continued movement of the cylinder assemblyand arms 43, toward the left, due to the expansion of the fluid withinthe device 29, will interrupt the operative relation between contacts 4|and 42 and thus disconnect the supply of energy to the heating elements52. The fluid within the device 20 will then contract due to the coolingeffect of the air passing f constant at the low value.

Should it be desired to secure an intermediate pitch setting of theblades, the switches 49 and 50 being opened, the switch 48 is closed tocomplete a circuit to the heating elements 52 through the lowerresilient member 44, it being pointed out that the contacts 4| and 42will have been closed due to the outward movement of the members I 4. Asabove described, in connection withthe operation of the mechanism forsecuring a low pitch of the blades, the cylinder assembly will bemaintained in such a position that the engagement between the contacts4| and 42 will be alternately made and broken at a positioncorresponding to the location of the stops 4'! associated with the lowerswitch housing 40, and the pitch of the blades will be substantiallyconstant at an intermediate value.

In the event that it is desired to completely reverse the pitch of theblades, the switch 50 is closed to energize the elements within theswitch housing 38 and to thus supply current to the heating devices 52.In this instance, the cylinder assembly will be maintained in an extremeposition toward the left and the shaft I 5 will cooperate with the lowerportions of the slots 16 and I! to reverse the pitch of the blades.

There is thus provided by the present invention a novel variable pitchpropeller embodying centrifugally operated members for securing avariation in the pitch of the blades. The provision of the fluidpressure operated control mechanism whereby the effect of thecentrifugallyresponsive members may be readily regulated, enables thepitch changing operation to be effected in a simple and efficientmanner. The use of the electrical means for regulating or controllingthe operation of the fluid pressure operated mechanism and embodyingselectively operable switches renders it possible to predetermine thepitch to which the blades are to be adjusted.

Though there has been illustrated and described only one embodiment ofthe invention, it

- is to be understood that the same may be capable of expression invarious forms, as will now be understood by those skilled in the art,without departing from the spirit thereof. Reference will therefore behad tothe appended claims for a definition of the limits of theinvention.

-Whatisclaimed is:

1. A variable pitch propeller comprising a plurality of blades, meansfor rotating said blades, means responsive to centrifugal force forvarying the pitch of said blades, means operable in accordance with theexpansion of a fluid for controlling. the operation ofsaidcentrifugally-responsive means, and means for controlling theexpansion of said fluid, said last-named means including a heatingelement, and means for sunplying electrical'energy to said element.

2. A variable pitch propeller having a plurality of blades, a rotatableshaft, means for drivably connecting said shaft and blades, means forrotating said blades about their longitudinal axes to increase thepitch, said means comprising her.

.said blades and shaft, said blades being rotatably mounted in said hub,and means for varying the pitch of said blades, said means includingcentriiugally-responsive members completely surrounding said blades andmovable axially thereof, and control means for said members including afluid pressure operated switch.

4. In combination, a rotatable shaft, a plurality of propeller blades, ahub for drivably connecting said blades and shaft, said blades beingrotatably mounted in said hub, means for varying the pitch of saidblades, said means including centrifugally-responsive members completelysurrounding said blades and movable axially thereof, control means forsaid members comprising a thermally-responsive mechanism, together witha fluid pressure operated switch.

5. In combination, a rotatable shaft, a plurality of propeller blades, ahub for drivably connecting said blades and shaft, said blades beingrotatably mounted in said hub, means for varying the pitch of saidblades, said means including centrifugally-responsive members completelysurrounding said blades and movable axially thereof, and athermally-responsive control mechanism for controlling the operation ofsaid centrifugallyresponsive members; said mechanism including a fluidpressure operated switch.

6. In a variable pitch propeller having a plurality of blades, means forvarying the pitch of said blades while the propeller is in operation,said means including centrifugally-responsive members completelysurrounding said blades and movable axially thereof, expansible meansfor controlling the operation of said members, and selectively operablecontrol mechanism including a fluid pressure operated switch forpredetermining the extent of operation of said expansible means.

7. In a variable pitch propeller having a plurality of blades, meansincluding expansible and contractible means for varying the pitch ofsaid blades, and means for selectively applying heat to said expansibleand contractible means including relatively movable switch contacts, oneof said contacts being carried by a part of said pitch-varying means andmovable therewith.

8. A variable pitch propeller comprising a rotatable shaft, a hubdrivably connected therewith, a plurality of propeller blades rotatablymounted in the hub, and means for rotating said blades in the hub tovary the pitch, said means including a fluid operated device, and anelectrical circuit for controlling the operation of said device, saidcircuit including a pair of relatively movable contact members, one ofsaid members being carried by a movable portion of said device.

9. In a variable pitch propeller having a plurality of blades, ahubhaving socket portions adapted to receive said blades, means forvarying the pitch of said blades, said means including acentrifugaily-responsive member surrounding each socket and operativelyconnected to the blade associated therewith, and fluid operated meansfor controlling the operation of said mem- 10. A device of the characterdisclosed comprising in combination a drive shaft; a hub mounted uponsaid shaft; a plurality of propeller blades mounted upon said hub; saidpropeller blades being relatively rotatable about an axis bladesincluding collars carried by said hub and coacting with said blades;means for changing the effective pitch of said propeller blades; saidmeans including members completely surrounding said blades and movableaxially thereof in response to centrifugal force to counteract thetendency of the propeller blades to 'move to a difierent pitch anglewhile in motion, and means including a fluid pressure operated switchfor variably controlling said members. 7

11. A device of the character disclosed comprising in combination adrive shaft; a hub mounted upon said shaft; a plurality of propellerblades mounted upon said hub; a plurality of collars carried by said huband coacting with said respect to said hub.

blades to prevent axial movement of said blades; said blades whenrotated tending to twist in one direction; means for relatively rotatingsaid blades about an axis transverse to the axis of said drive shaft;and means movable axially of said blades to neutralize the force tendingto twist said blades.

12. In a. propeller structure, the combination of a shaft for rotatingsaid propeller; a hub structure having extensions and carried by saidshaft; adjustable blades mounted in said hub extensions; means foradjusting said blades while the propeller is in motion; said meansincluding means movable axiallvof said shaft, means movable axially ofsaid extensions and operating connections therebetween, and means on theexterior of said hub to positively position said blades with JAMES M.MILLS.

